JPH0416906A - Manufacture of plastic optical fiber - Google Patents

Abstract

PURPOSE:To obtain an optical fiber in which optical transmission loss is reduced by employing specific polycarbonate group resin as a coating raw material and transparent resin with refractive index less than that of the coating material as a sheath raw material, and molding them as a core material and a sheath material, respectively. CONSTITUTION:The polycarbonate group resin of powder shape in-cluding grain >= 90wt.% without receiving temperature history exceeding a crystal m.p. and whose grain diameter of mesh>= 32 is employed as the coating raw material, and the transparent resin with refractive index less than that of the coating material as the sheath raw material, and they are molded as the coating material 2 and the sheath material 3, respectively. Thereby, it is possible to obtain a plastic optical fiber suitable for the one used in a home electronic field or an automobile field, for example, the one arranged in the engine room of an automobile, and with small amount of optical transmission loss, and also, with superior heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a method of manufacturing a plastic optical fiber.

More specifically, this invention produces a plastic optical fiber with low optical transmission loss and excellent heat resistance, which is suitable for the home appliance field and the automobile field, for example, as a plastic optical fiber installed in the engine compartment of a car. Regarding the method.

[Prior art and the problem to be solved by the invention] In recent years,
As optical fibers for light transmission, plastic optical fibers have been developed and put into practical use because they are more resistant to bending stress, easier to connect and handle, and are less expensive than the inorganic glass optical fibers that have been widely used for a long time. There is.

This plastic optical fiber consists of a core material made of a polymer with excellent light transparency and a sheath material layer made of a polymer with a lower refractive index than the core material and excellent transparency. Until now, polymethyl methacrylate core materials have been developed, and due to their poor heat resistance, they have not been able to be used around automobile engines.

On the other hand, plastic optical fibers with improved heat resistance by using polycarbonate resin as the core material have been proposed (Japanese Patent Laid-Open No. 61-6604,
(Refer to Publication No.-262706).

However, for example, according to Japanese Patent Application Laid-Open No. 61-6604, a plastic optical fiber with excellent mechanical properties, especially tensile strength, can be obtained by using a polycarbonate resin with an intrinsic viscosity [η] of 0.5 as the core material. However, the plastic optical fiber has an optical transmission loss of 990 dB/km at an optical wavelength of 770 ns, which is not a sufficiently small value.

On the other hand, for example, according to Japanese Patent Application Laid-open No. 61-262706, the optical transmission loss for an optical wavelength of 770n is 660 dB.
Plastic optical fibers as small as /km have been obtained. Furthermore, a method for manufacturing a plastic optical fiber is disclosed, which comprises selecting and using polycarbonate, which has not been heated to a temperature exceeding its crystal melting point, as a component for the core material, and melt-spinning this polycarbonate.

However, in this manufacturing method, there is no description of the particle size distribution of the polycarbonate, and there is also the problem that this plastic optical fiber does not have sufficient optical transmission characteristics.

This invention has been made based on the above circumstances.

An object of the present invention is to provide a method for manufacturing a plastic optical fiber that reduces optical transmission loss and has excellent heat resistance.

[Means for Solving the Problems] The present invention for solving the problems described above provides a powder-like material that is not subjected to a temperature history exceeding the crystal melting point and that has a particle size of 32 mesh or more or more than 90% by weight. A method for producing a plastic optical fiber, which comprises using a polycarbonate resin as a core material raw material, a transparent resin having a lower refractive index than the core material as a sheath material raw material, and molding these into a core material and a sheath material, respectively. be.

The structure of the plastic optical fiber obtained by the manufacturing method of the present invention is, for example, as shown in FIG.
and a sheath material layer 3 as its outer layer, and may further have a protective layer 4 as an outer layer of the sheath material layer 3 as required, as shown in FIG. 2, for example. .

Hereinafter, the core material and sheath material layers will be explained in detail, and the manufacturing method will also be explained in detail.

The core material may be made of a polycarbonate resin, or one or more polycarbonate resins may be selected from among various known polycarbonate resins, or two or more types may be selected as needed.

Specific examples of the polycarbonate resin include various types, preferably alicyclic polycarbonates whose repeating units are represented by the following general formula: Examples include aromatic polycarbonates, which are aromatic polycarbonates.

Furthermore, copolymers of these and dihydroxy compounds such as 4.4°-dihydroxydiphenyl ether, ethylene glycol, p-phenylene glycol, and 1,6-hexanediol can also be used. The polycarbonate resin may have a partially branched structure.

There are no particular limitations on the method for producing the polycarbonate resin in the present invention, and for example, a phosgene method involving a reaction between dihydric phenols and phosgene may be employed.

The dihydric phenols include hydroquinone, 4,
4'-dihydroxybiphenyl, bis(hydroxyphenyl)alkane, bis(hydroxyphenyl)cycloalkane, bis(hydroxyphenyl)ether, bis(
Examples thereof include hydroxyphenyl) sulfide, bis(hydroxyphenyl)sulfone, and substituted products thereof such as lower alkyl and herogen.

Among these dihydric phenols, for example, 2.2
-Bis(4-hydroxyphenyl)furopane [hereinafter sometimes referred to as bisphenol A]. ], l, 1-bis(
4-hydroxyphenyl)ethane, 2,2-bis(4-
Preferred are hydroxyphenyl)-hexafluoropropane and the like.

Further, these dihydric phenols may be used alone or in combination.

The polycarbonate resin used for the core material preferably has a molecular weight within a suitable range among the above, and generally has a viscosity average molecular weight of 20,000 to 28,000,
000 is preferable, especially 20,
Those within the range of 500 to 27,000 are preferred.

The viscosity average molecular weight is determined by measuring the specific viscosity ηsp of a methylene chloride solution at 20°C and calculating the following formula (1 formula % formula %): C: Polycarbonate resin concentration (g/JN and [η] = 1.23X 10-'MvO" It can be found by .

The polycarbonate resin used for the core material has a viscosity average molecular weight of 20,000 to 28,000, for example.
Sufficient strength and good moldability of the two-plastic optical fiber can be easily ensured by using a material within an appropriate range, such as within the range of
Improvements in optical properties such as transparency, refractive index, and optical transmission loss of plastic optical fibers can also be easily ensured.

The viscosity average molecular weight of the polycarbonate resin can be easily adjusted by adjusting the amount of a terminal capping agent such as p-tert-butylphenol in the polymerization reaction during the production of the polycarbonate resin. can.

In addition, the polycarbonate resin used for the core material has a weight average molecular weight (M w
) and the number average molecule ti (M n ) [M w /
M n (GPC method)] is preferably within the range of usually 2.0 to 2.6, particularly preferably within the range of 2.0 to 2.4. Further, the polycarbonate resin can be obtained by treating the polymer obtained during production with a solvent such as acetone to obtain a low molecular weight component [M w ;
3,000 or less] is preferably removed.

Furthermore, it is preferable that the polycarbonate resin has been sufficiently desalinated, for example, it is preferable that the content of herogenated hydrocarbons is 15 ppm or less.

The foreign material strength of the polycarbonate resin constituting the core material in the present invention is preferably l x 105) 105) h or less, particularly preferably 5 x 10' JLm2/g or less.

Here, the foreign matter strength is expressed as the integrated value of the cross-sectional area and number of foreign matter having a particle size of 0.5 to 25 gm in an organic solvent (methylene chloride) solution.

An example is as follows.

d, Two particle size classification values (in m) n3: Concentration of foreign substances with particle diameters d, ~d, (pieces/g) Set particle size classification value dr = 0.5 (jlrn) d6 = 5.
0 (gm) da =0.6 (gm) dt =
IO, O (gm) d x =0.7 (jam)
da = 20.0 (gm) d4 = 1.1 (fiL
m) d9 = 25.0 (gm) d5 = 2.0 (
uLm) Identification of the average molecular weight of the core material and foreign matter strength 1×1 (15
By being less than gm2/g, sufficient strength and good moldability of the plastic optical fiber can be easily ensured, and the optical transmission loss of the plastic optical fiber can be further reduced.

Furthermore, by forming the core material from the polycarbonate resin, its refractive index can be made to a sufficiently high level as a core material of an optical fiber. This refractive index varies depending on the type of polycarbonate resin used, and in the case of bisphenol A polycarbonate, it usually has a value of around 1.586.

On the other hand, from the perspective of heat resistance, the heat distortion temperature is 12
It is preferable to use a polycarbonate resin having a temperature of 0° C. or higher. Here, heat distortion temperature is ASTM D
-648, and refers to the measured value at a load of 4.6 kg/cm2.

Here, an important point in the present invention is that the raw material polycarbonate resin constituting the core material is a particle that has not been subjected to a temperature history exceeding the crystal melting point.

As mentioned above, it is advantageous to use a resin derived from bisphenol A as the polycarbonate resin used in the present invention. Most preferably, polycarbonates prepared by interfacial polycondensation at temperatures below 5[1''C are used.

At the end of the reaction, the polymer polymerized by this method exists as a solution in an organic solvent such as methylene chloride, and unreacted substances and by-products are removed from this polymer solution by washing, followed by spray-try and devolatilization. The solvent is separated and the polymer is recovered using various methods such as extrusion and precipitation. Usually, polycarbonate used as a molding material is added to the recovered polymer and stabilizers such as an antioxidant stabilizer and an ultraviolet absorber, and then molded into a bereut shape by melt extrusion. When molding into pellets, it is essential to heat the polycarbonate to a temperature higher than its crystal melting point (differential thermal balance method) of 245°C to melt it, and polycarbonate usually has a temperature of 280 to 3
The current situation is that it is unavoidable that polymers undergo thermal decomposition when exposed to high temperature thermal history of 20°C. Therefore, even if a molded pellet of polycarbonate containing such a thermal decomposition product is used and an optical fiber is obtained by melt spinning, it will not be possible to obtain an optical fiber with excellent light transmission properties. - Particularly when using polycarbonate molded into pellets,
The optical transmission properties of visible light at 0 and 660 ns are reduced.

In the present invention, in order to obtain an optical fiber with excellent optical transmission properties in the visible light region, it is important to keep the thermal history of the polycarbonate core to the necessary minimum number of times and temperature. It is advantageous to directly melt-spun the polymer without forming it into pellets.

An important point when using the powdered polycarbonate recovered at this time as the core material is that the powdered polycarbonate should contain particles with a particle size distribution of 32 mesh or more or 90% by weight or more. It is to use.

If the particle size distribution is 32 mesh or more or 90% by weight, the extrusion variation will be large and the diameter variation will be large.
Further, fine particles may enter between the thrust shaft of the screw and the cylinder, increasing the amount of foreign matter and increasing optical transmission loss.

Here, the upper limit of the particle size of the powdered polycarbonate is sufficient as long as it can fit into the extruder and does not affect the properties of the optical fiber.

The powder has a particle size distribution of 32 mesh or more.

When the powdery polycarbonate contains a large amount of fine powder, it can be obtained by classifying it in a clean room using a 32-mesh sieve.

Sheath L layer The sheath material layer has a refractive index smaller than that of the core material, specifically, 0.01 or more than the refractive index of the core material, preferably 0.0.
A resin having a refractive index smaller than 2 [hereinafter sometimes referred to as resin (A)]. ] Consists of.

By making the refractive index of the resin (^) smaller than the refractive index of the core material, the resin (A) can be used as a sheath material layer in a plastic optical fiber, and the optical fiber has low optical transmission loss. It can be done.

There is no particular restriction on the type of resin (A) constituting the sheath material layer, but specific examples include polymethyl methacrylate, poly-4-methylpentene-1, polyarylate, alicyclic polycarbonate, and aromatic polycarbonate. Polycarbonate, silicone resin.

silicone acrylate resin, urethane acrylate resin, fluorine-containing polymethyl methacrylate, vinylidene fluoride polymer, vinylidene fluoride-hexafluoropropylene copolymer, styrene-methyl methacrylate copolymer, ethylene-vinyl acetate copolymer, Examples include methyl methacrylate/styrene, vinyltoluene or α-methylstyrene/maleic anhydride ternary or quaternary copolymers.

These polymers are used to improve delamination strength.
Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and itaconic acid, unsaturated glycidyl monomers such as diglycidyl acrylate or methacrylate, β-methylglycidyl acrylate or methacrylate, acrylamide, methacrylamide, and derivatives thereof, hydroxyalkyl acrylate, or methacrylate It is also possible to copolymerize a wood-loving upper layer such as.

Examples of highly versatile materials include methacrylic copolymers such as polymethyl methacrylate, and polymers obtained by polymerizing esters of methacrylic acid and fluorinated alcohols.

Specific examples of the esters include methacrylic acid 2,2
．． 2-)-Lifluoroethyl, methacrylic acid 2,2,3
．． 3-tetrafluoropropyl, methacrylic acid 2,2,
3,3,3-pentafluoropropyl and the like can be mentioned.

By using one or more of these fluorine-containing methacrylic esters, a copolymer consisting of a vinyl monomer that can be copolymerized with the fluorine-containing methacrylic ester and a vinyl monomer that can form a wood-philic homopolymer can be produced. You can also use

Among these resins, a resin having a refractive index smaller than that of the core material can be used as the resin (A).

i51 The plastic optical fiber of the present invention may further have a protective layer as an outer layer of the sheath material layer, if necessary.

The protective layer is made of a resin [hereinafter referred to as resin (B)] having heat resistance equal to or higher than the heat deformation temperature of the core material and the sheath material layer.
There is something to be said. ] It is preferable.

The heat resistance of the plastic optical fiber can be improved by setting the heat deformation temperature of the resin (B) higher than that of the sheath material layer.

Examples of the resin (B) include polyester, polyamide, poly-4-methylpentene-1, polyvinyldene fluoride, polyacetal, polysulfone, polytetramethylene terephthalate, polyethylene terephthalate, polypropylene, polyoxymethylene, polybutene, Examples include so-called engineering plastics such as ABS resin, polyphenylene oxide, polycarbonate, and crosslinked polyolefin. It is also possible to use polycarbonate resin used as a core material.

Furthermore, in order to improve the durability of the plastic optical fiber, the resin (B) may contain fillers such as carbon black, talc, silica, glass fiber, carbon fiber, and polyamide fiber.

1 Manufacturing method As described above, the plastic optical fiber of the present invention has a core material made of a polycarbonate resin and a sheath material made of a resin having a refractive index lower than that of the core material. Particles that have not undergone a temperature history exceeding Something will happen.

Furthermore, the plastic optical fiber of the present invention can be produced by using, for example, a composite spinning machine 5 as shown in FIG. Melt extruder 6b as raw material
supply to. Composite spinning is carried out so that the polycarbonate resin is coated with the resin (A) from the nozzle 7, which is taken up by a take-up machine 8, and cooled between the nozzle 7 and the take-up machine 8 (air gap 9). It is manufactured by spinning while spinning.

In the manufacturing method of this invention, the temperature of the nozzle is set to 235
Composite spinning is carried out within the range of ~280°C. Furthermore, composite spinning is preferably carried out at a nozzle temperature within the range of 240 to 270°C.

Further, in the manufacturing method of the present invention, composite spinning is performed while cooling with an air gap of 700 to 1,300 mm.

Extrude by keeping the nozzle temperature within the range of 235-280℃, and the air gap is 700-1,300mm.
By doing so, it is possible to always stably and easily manufacture plastic optical fibers with small fluctuations in roundness and outer diameter and low optical transmission loss.

Cooling in the air gap may be natural cooling at room temperature or forced cooling. In addition, in composite spinning,
A spinning tube may be provided in a part between the nozzle and the take-off machine.

In addition, the polycarbonate resin supplied to the melt extruder 6a has a particle size distribution of 32 meshes or more.
It is important that the granules contain 0% by weight or more (unmelted).

The bulk density of the polycarbonate resin granules is from 0.6 to
It is preferable that it is 0.8 g/c+a:I.

The bulk density of the polycarbonate resin granules is 0.6~
At 0.8 g/ca+'', the resin can be fed to an extruder in the same manner as a general pellet-shaped resin, and the resin can be extruded stably.

An example of the structure of a plastic optical fiber manufactured in this way is an outer diameter of 400 to 1.000 μm;
The thickness of the sheath material layer is 1 to SOBm.

Furthermore, a plastic optical fiber having a protective layer can be manufactured by further covering the sheath material layer with a protective layer.

The plastic optical fiber of this invention has mechanical strength,
Due to its excellent heat resistance and low optical transmission loss, it is suitable for use in fields where conventional plastic optical fibers have not been able to be used, such as in the electrical, electronic, and automotive fields, as a sensor means and optical communication means. I have something to do.

[Example] Next, an example of the present invention will be shown and the present invention will be explained in more detail.

(Example 1) (1) Production of polycarbonate resin powder) A polycarbonate solution obtained by reacting bisphenol (A) with phosgene in the presence of a caustic sorter aqueous solution and methylene chloride was filtered through a 0.2 pm filter. Ta.

Then, powdered polycarbonate was obtained by hot water granulation. This powdered polycarbonate is converted into polycarbonate (
A).

Viscosity average molecular weight foreign material strength of the obtained polycarbonate,
Particle size distribution was measured as follows.

Viscosity average molecular weight: Measure the specific viscosity ηsP of a methylene chloride solution at 20°C, and use the formula ηsp/C=[η](1+0.28η5p)C; polycarbonate resin concentration (g/K).

[η] = 1.23X10-'Mv'''.

Foreign material strength: The obtained polycarbonate was dissolved in methylene chloride filtered through a 0.2 pm filter, and the diameter and number of foreign materials were measured using a liquid particle counter, and determined by the above-mentioned formula.

Particle size distribution: Determined by sieving the polycarbonate obtained above using a 32 mesh sieve.

(2) Production of plastic optical fiber The polycarbonate (A) was supplied as a raw material resin for a core material to a melt extruder 6a set at 270°C.

Poly-4-methylpentene-1 was set at 310° C. as a raw material resin for the sheath material layer and supplied to the melt extruder 6b.

The nozzle diameter is 3■■ so that the core material of polycarbonate resin is covered with the sheath material layer of poly-4-methylpentene-1.
Extrude from the φ mouthpiece (nozzle 7) and use the take-up machine 8 to remove 20
It was taken up at a speed of m/min and composite spinning was performed.

In addition, the nozzle temperature was set to 250°C, the air gear love 9 was set to 1.000cm-, and the diameter of the core material was 98cm.
A plastic optical fiber having a thickness of 0 gm and a sheath layer thickness of 10 pm was obtained.

The optical transmission loss of the obtained plastic optical fiber was measured using light having a wavelength of 6600 cm.

Furthermore, the variation in the outer diameter of the obtained plastic optical fiber was measured using a laser outer diameter measuring device.

Next, the extruder for the sheath material layer was stopped, and the polycarbonate core material was sampled in a clean room, and its foreign material strength was measured.

The above results are shown in Tables 1 and 2.

(Example 2) (1) Production of polycarbonate resin powder Powdered polycarbonate was obtained from the filtrate in (1) of Example 1 by changing the granulation conditions.

Next, the polycarbonate powder was classified using a 32-mesh sieve in a clean room, and a 32-mesh sieve was used.
Polycarbonate powder was obtained.

This powdered polycarbonate (polycarbonate) (
B).

(2) Production of plastic optical fiber In Example 1, polycarbonate (A) was replaced with polycarbonate (B).
) The procedure was the same as in Example 1 except that .

The results are shown in Tables 1 and 2.

(Comparative Example 1) (1) Production of polycarbonate resin powder The polycarbonate powder before classification in Example 2 was used as polycarbonate (C).

(2) Production of plastic optical fiber In Example 1, polycarbonate (A) was replaced with polycarbonate (C).
The same procedure as in Example 1 was carried out except that .

The results are shown in Tables 1 and 2.

(Comparative Example 2) (1) Production of polycarbonate resin powder The polycarbonate (B) in Example 2 was pelletized in a clean room using an extruder with a diameter of 10 mm.

This pellet was made of polycarbonate (D).

(2) Production of plastic optical fiber In Example 1, polycarbonate (A) was replaced with polycarbonate (0).
The same procedure as in Example 1 was carried out except that .

The results are shown in Tables 1 and 2.

FIG. 2 FIG. 3 [Effects of the Invention] According to the present invention, a plastic optical fiber with low optical transmission loss can be provided.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory cross-sectional views showing an example of a plastic optical fiber manufactured by the manufacturing method of the present invention. FIG. 3 is an explanatory diagram showing an example of an apparatus used in the manufacturing method of the present invention. 1...Plastic optical fiber, 2...Core material, 3
... Sheath material layer, 4... Protective layer, 5... Composite spinning machine,
6a, 6b... melt extruder, 7... nozzle, 8...
...Takeover machine, 9...Air gap. ,y=-,ノ,! ' July 6, 1990

Claims (1)

[Claims] (1) Using a powdered polycarbonate resin as a core material raw material, which is not subject to temperature history exceeding the crystal melting point and whose particle size is 90% by weight or more and whose particle size is 32 mesh or more,
A method for producing a plastic optical fiber, which comprises using a transparent resin having a lower refractive index than the core material as a raw material for the sheath material, and molding them into a core material and a sheath material, respectively.